Apparatus for milling asbestos cobs and like fibrous ore bodies



Nov. 16, 1954 N. ANDERSON APPARATUS FOR MILLING ASBESTOS COBS AND LIKE FIBROUS ORE BODIES Filed Jan. 26. 1951 s 314M K r GM.

Unite Nigel livari Anderson, Braamfontein, Johannesburg, Union of South Africa Application January 26, 1951, Serial No. 207,962

Claims priority, application Union of South Africa December 13, 1950 Claims. (Cl. 241-40) This invention relates to an apparatus for milling asbestos cobs and like fibrous ore bodies.

The normal method of milling is to feed the cobs into a jaw-crusher and thence into a hammer mill in order to crush and break up the cobs and loosen the foreign matter from the fibres. The hammers of the mill and, to some extent also, the jaws of the crusher are subjected to an extreme degree of war and tear with the result that frequent replacements, particularly of the hammers, are necessary. This adds materially to the working costs.

A further disadvantage inherent in the normal method is that the quality of the fibres is adversely affected, especially as regards uniformity, by the repeated blows of the hammers to which the cobs are subjected.

The present invention aims at minimizing these disadvantages.

The invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a vertical section through a milling apparatus.

Fig. 1(a) shows the hopper, portion of which appears in Fig. 1.

Fig. 2 is a cross-section taken on the line 11-11 in Fig. 1, and P Fig. 3 is a cross-section taken on the line III-III in Similar numerals refer to similar parts throughout the different views.

The casing comprises a central materially tubular por tion 1 and upper and lower frustro-conical portions 2 and 3 respectively. The upper portion 2 is removably attached to the central portion 1 by bolts 4. The central portion 1 is formed internally with a shoulder 5 upon which an annular hard metal ring 6 constituting an impact surface is supported. Such ring may easily be replaced when worn.

Air is arranged to be forced into the interior of the casing through a duct 7, the upper or inner extremity of which is axially disposed with respect to the casing and flared outwardly as shown at 8. Stay members 9 support an inverted conical batfle 10 within the casing, the function of the batfle being to deflect the air passing through the duct 7 into the annular passage 11 between the periphery of the battle and the wall of the central portion 1 of the casing.

An inverted frustro-conical ring 12 is carried axially within the casing on bolts 13 which pass through the casing and by means of which the longitudinal position of the ring 12 may be adjusted to vary the width of the aforesaid annular passage 11. The upper limit of the permissible longitudinal movement of the ring 12 is indicated by the chain-dotted lines 14.

The bottom extremity of the lower frustro-conical portion 3 of the casing is arranged for connection by bolts 15 to an axial extension 16 through which waste products are discharged in manner described below. A vaned rotor 17 is mounted for rotation Within the extension 16 as shown.

The top extremity of the upper frustro-conical portion 2 of the casing is arranged for connection by bolts 18 to a duct member 19 which is formed with an upwardly extending axial bush 20 in which a tubular member 21 is rotatably mounted. The lower part of such tubular member 21 is bent at right angles in a smooth curve so States Patent 0 that the discharge end 22 is in the same transverse plane as, and extends radially towards, the hard metal ring 6.

retested Nov.- 15, 1954.

Z The tubular member 21 is provided with a housing com: prising an upper frustro-conical portion 23 and a lower circular portion 24, said housing and tubular member being arranged to rotate together. A balance weight 25 is positioned within the housing as shown.

A bush 26 is secured by bolts 27 to the conical baffle 10 to which is welded a ring 28. A spigot member 29, the upper end of which is formed with a hollow boss 30 is carried in the bush 26 and is prevented from rotating therein by means of a key 31. Bolts 32 serve to clamp the outer race 33 of an anti-friction bearing 34 between a shoulder 35 in the boss 30 and an annulus 36.

An annulus 37 is mounted transversely within the circular portion 24 of the housing and bolts 38 to secure the annulus to a plate 39 which carries a stub axle 40 which is mounted for rotation in the bearing 34. The lower end of the stub axle 40 is threaded at 41 for reception of a nut 42. Sealing pads 43 and a throw-off disc 44 are provided as shown. The lower end of the circular portion 24 of the housing is provided with an inwardly extending flange 45 which is coplanar with the ring 28.

The upper portion of the tubular member 21 is formed with an external taper 46 on which the inner race 47 of a tapered anti-friction bearing 48 is carried. The outer race 49 of such bearing is clamped between an annulus 50 and a hollow boss 51 which latter is secured, as by welding, to the bush 20. Sealing rings 52 and a throw- Off disc 53 are provided as shown. 54 is a flanged distance-piece and 55 a pulley which is keyed at 56 to the tubular member 21. Bolts 57 which pass through the pulley 55 and an annulus 58 serve to press the bearing 48 down onto the taper 46, the force being transmitted through the distance-piece 54.

The upper end of the pulley 55 is provided with a hollow boss 59 which receives a non-rotatable hopper 60 having an internal transverse grid structure 61 to prevent the ingress of unduly large cobs.

In operation, rotation is imparted to the tubular member 21 and its housing by a prime mover 62 connected by V-belts 63 to the pulley 55. Asbestos or like cobs are fed into the hopper 60 and they pass through the tubular member 21 to be discharged radially therefrom and hurled by centrifugal force against the ring 6. The force of impact fractures the cobs and the fibres are carried off through the duct member 19 by the air stream flowing upwards through the annular passage 11. The foreign matter, being of greater density, falls downwards through the passage 11 against the air flow and is with drawn from the apparatus by the vaned rotor 17.

It is important to note that each cob is subjected to but a single blow, which is highly advantageous in securing uniformity of the fibrous product.

Further treatment of the fibres discharged from the duct 19 may be effected in known manner.

I claim:

I. An apparatus for milling asbestos-cobs and like ore bodies comprising a casing having a vertical axis, a ringshaped impact surface within said casing, a single tubular member extending axially into said casing, said tubular member provided with an inner portion which is bent in a smooth curve to provide a discharge orifice within said casing which is disposed in a plane substantially perpendicular to the longitudinal axis of said casing, said ring-shaped impact surface being provided in the same substantially perpendicular plane as the discharge orifice of said tubular member, and a prime mover to rotate said tubular member relative to said casing about its vertical axis so that said ore bodies are fractured by being hurled outwardly against said impact surface to loosen the fibers therefrom and means for passing a stream of air through the milled cobs and bodies to separate the fibers from the foreign matter therein.

2. An apparatus according to claim 1, including a conical baflie mounted within the casing, said battle being arranged to deflect the air stream towards the gap between the impact surface and the orbital path of the discharge orifice of the tubular member.

3. An apparatus according to claim 1, including vaned rotor means for withdrawing foreign matter from the References Cited in the file of this patent UNITED STATES PATENTS Date Number Name Chichester Aug. 15, 1882 Number 10 Number Name Date Sturtevant May 17, 1921 Simpson Nov. 10, 1925 Cummins Nov. 7, 1933 Fraser Jan. 30, 1940 Wall Jan. 23, 1945 Koehne June 28, 1949 FOREIGN PATENTS Country Date Great Britain Jan. 6, 1927 Germany Feb. 14, 1940 France Aug. 23, 1945 

